A recent genome-wide meta-analysis has identified a biological commonality among 120,000 regular coffee drinkers - 6 new genetic variants related to caffeine metabolism, lipid and glucose metabolism, and its psychoactive effects, found among about 2.5 million variants in the genome.

The researchers believe it may explain why different people have different reactions to coffee - some papers have even found an increased risk of death and they explain 1.3 percent of our coffee-drinking behavior. If that doesn't sound like a lot, it is the same genetic basis for smoking.

Those different reactions are why there is some disagreement about the health effects of coffee. 

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One of the gene variations suggested to impact the rewarding effects of caffeine is near the brain-derived neurotrophic factor (BDNF) protein, which promotes the survival of neurons, is active at snyapses and helps regulate synaptic plasticity for learning and memory. The other is near solute carrier family 6 neurotransmitter transporter, member 4 (SLC6A4), a serotonin transporter, which also affects synapses and neurons. Because they are in regions of the brain linked to control of eating and drinking, the assumption is they contribute to weight management - and therefore what you like to eat and drink.

What was interesting was people who had 5 of the 6 single-nucleotide polymorphism (SNPs) were more likely to be heavy coffee drinkers (4 cups per day or more) than people who only had one or two of the gene variants. It isn't a taste issue, none of the genes were related to that. But it could explain why some people feel energized with a single cup of coffee and some people want more, like 4 cups, or a high-caffeine energy drink. The assumption had been just gradual tolerance level increase rather than a genetic factor.

Need more coffee science? Here are some other samples.

Coffee is healthy:

Coffee Makes Us Want To Be Worthy Of It:

Coffee Makes Us Love Each Other:

Coffee Improves Race Relations:

Coffee Protects Us:

Coffee Is Good For The Global Economy:

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